Typically you want to minimize url length by removing stop words, prepositions, etc. unless they are creating value within the URL.      e.g.  bunny-on-stool  vs. bunny-stool

I wouldn't go as far as to say it is bad for SEO, but there are some schools of thought that minimizing the number of words in a URL "concentrates" relevance around those terms remaining.   That being said, I'm confident Google already ignores common stop words and phrases, and this isn't something I would go about changing in an existing URL structure.

You'll notice some sites, such as wordpress, by default remove the prepositions, etc. from the URLs.

Do you know what the redirect type is (301 or 302)? If it is a 301, I wouldn't worry about it. If it is a 302, I'd try and get that changed. Either way, it is unlikely to make a big impact on your site.

1. Add tags to each article that link off to related content (an easy way is to just have it link to your site search results for that tag)

2. Increase internal linking in the content of your articles to other pages on your site to coax users into reading more.

3. Include "related pages" or something similar at the end of every piece of content published on your site.

4. Add "popular pages" to the sidebar to catch people who might simply find your most popular information interesting.

I wouldn't worry about it. Your site is indexed in Google and is, likely, cached. Just because Google's cache: operator isn't working properly for you at the moment isn't a real cause of concern.

Search Suggest is also dependent upon the volume of content related to those keywords. Remember, the original search suggest provided you with data on the number of search results available for the phrase. We have seen marginal improvement with just massive content syndication and no click manipulation.

Finally, whatever you do, it will have to be sustained. Suggest is updated alongside whatever keyword metrics Google is using. You can't simply hope to run a single mechanical turk campaign and then permanently influence the results.